Abstract The overarching purpose of this proposal is to produce a universal influenza vaccine using a new micro-particle-adjuvant combination that generates dramatic dose-sparing and robust immune enhancement effects. Influenza virus is a recurrent public health threat of international concern. Current influenza viral vaccines are comprised of life attenuated virus, inactivated influenza vaccine or recombinant influenza protein vaccine. The latter usually requires an adjuvant. However, a major challenge is that dominant flu vaccine antigens such as hemagglutinin are highly variable among different influenza strains, and hence new vaccines have to be produced annually. There is a national push for an alternative approach relying on a universal influenza vaccine. This approach involves common antigens that are shared among different influenza strains, but faces a major hurdle in that these antigens are typically weakly immunogenic and requires a strong adjuvant for their efficacy, which has not been achieved to date. Microbial pathogen-associated molecular patterns (PAMP) are small molecules produced by microbes that stimulate the immune system, and these have emerged as strong adjuvants. However the receptors for many PAMPs reside in the cytosol, thus presenting a challenge for delivery. We have used a particle-based delivery system that successfully delivers PAMPs inside the cell to activate their respective receptors. This produces a robust adjuvant effect that does not cause toxicity or systemic inflammation. In the context of hemagglutinin, this microparticle-PAMP combination enhances specific antibody response up to 105 fold over bare antigen, induces a strong T cell response and fully protects infected mice and ferrets. This proposal plans to use this platform in a universal influenza vaccine. To advance this vaccine platform towards pre-IND development, we have a regulatory expert and a toxicologist guiding us throughout the proposal. In addition, a main industrial partner with expertise in particle production and other contract research organizations have been recruited to assist us towards the development of a lead universal vaccine. Thus, this proposal is fully responsive to the RFA-AI-17-042 and is focused on the preclinical development of a robust vaccine candidate that elicits strong T and B cell responses and cross-reacting antibodies to address one of the greatest public health concerns.